# Environmental engineering

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Environmental engineering is a professional engineering discipline that encompasses broad scientific topics like chemistry, biology, ecology, geology, hydraulics, hydrology, microbiology, and mathematics to create solutions that will protect and also improve the health of living organisms and improve the quality of the environment. [1] [2] Environmental engineering is a sub-discipline of civil engineering and chemical engineering.

## Contents

Environmental engineering is the application of scientific and engineering principles to improve and maintain the environment to:

• protect human health,
• protect nature's beneficial ecosystems,
• and improve environmental-related enhancement of the quality of human life. [1]

Environmental engineers devise solutions for wastewater management, water and air pollution control, recycling, waste disposal, and public health. [2] [3] They design municipal water supply and industrial wastewater treatment systems, [4] [5] and design plans to prevent waterborne diseases and improve sanitation in urban, rural and recreational areas. They evaluate hazardous-waste management systems to evaluate the severity of such hazards, advise on treatment and containment, and develop regulations to prevent mishaps. They implement environmental engineering law, as in assessing the environmental impact of proposed construction projects.

Environmental engineers study the effect of technological advances on the environment, addressing local and worldwide environmental issues such as acid rain, global warming, ozone depletion, water pollution and air pollution from automobile exhausts and industrial sources. [2] [6] [7] [8]

Most jurisdictions impose licensing and registration requirements for qualified environmental engineers. [9] [10] [11]

## Etymology

The word environmental has its root in the late 14th-century French word environ (verb), meaning to encircle or to encompass. The word environment was used by Carlyle in 1827 to refer to the aggregate of conditions in which a person or thing lives. The meaning shifted again in 1956 when it was used in the ecological sense, where Ecology is the branch of science dealing with the relationship of living things to their environment. [12]

The second part of the phrase environmental engineer originates from latin roots and was used in the 14th century French as engignour, meaning a constructor of military engines such as trebuchets, harquebuses, longbows, cannons, catapults, ballistas, stirrups, armour as well as other deadly or bellicose contraptions. The word engineer was not used to reference public works until the 16th century; and it likely entered the popular vernacular as meaning a contriver of public works during John Smeaton's time.

## History

### Ancient civilizations

Environmental engineering is a name for work that has been done since early civilizations, as people learned to modify and control the environmental conditions to meet needs. [3] [13] As people recognized that their health was related to the quality of their environment, they built systems to improve [3] it. The ancient Indus Valley Civilization (3300 B.C.E. to 1300 B.C.E.) had advanced control over their water resources. [13] The public work structures found at various sites in the area include wells, public baths, water storage tanks, a drinking water system, and a city-wide sewage collection system. [13] [14] They also had an early canal irrigation system enabling large-scale agriculture. [15]

From 4000 to 2000 B.C.E., many civilizations had drainage systems and some had sanitation facilities, including the Mesopotamian Empire, Mohenjo-Daro, Egypt, Crete, and the Orkney Islands in Scotland. [3] The Greeks also had aqueducts and sewer systems that used rain and wastewater to irrigate and fertilize fields. [3]

The first aqueduct in Rome was constructed in 312 B.C.E., and from there, they continued to construct aqueducts for irrigation and safe urban water supply during droughts. [3] They also built an underground sewer system as early as the 7th century B.C.E. that fed into the Tiber River, draining marshes to create farmland as well as removing sewage from the city. [3] [13]

### Modern era

Very little change was seen from the fall of Rome until the 19th century, where improvements saw increasing efforts focused on public health. [13] [16] Modern environmental engineering began in London in the mid-19th century when Joseph Bazalgette designed the first major sewerage system following the Great Stink. [13] The city's sewer system conveyed raw sewage to the River Thames, which also supplied the majority of the city's drinking water, leading to an outbreak of cholera. [13] The introduction of drinking water treatment and sewage treatment in industrialized countries reduced waterborne diseases from leading causes of death to rarities. [17]

The field emerged as a separate academic discipline during the middle of the 20th century in response to widespread public concern about water and air pollution and other environmental degradation. As society and technology grew more complex, they increasingly produced unintended effects on the natural environment. One example is the widespread application of the pesticide DDT to control agricultural pests in the years following World War II. The story of DDT as vividly told in Rachel Carson's Silent Spring (1962) is considered to be the birth of the modern environmental movement, [18] which led to the modern field of "environmental engineering."

## Education

Many universities offer environmental engineering programs through either the department of civil engineering or chemical engineering and also including electronic projects to develop and balance the environmental conditions. Environmental engineers in a civil engineering program often focus on hydrology, water resources management, bioremediation, and water and wastewater treatment plant design. Environmental engineers in a chemical engineering program tend to focus on environmental chemistry, advanced air and water treatment technologies, and separation processes.[ citation needed ] Some subdivisions of environmental engineering include natural resources engineering and agricultural engineering.

Courses for students fall into a few broad classes:

• Mechanical engineering courses oriented towards designing machines and mechanical systems for environmental use such as water and wastewater treatment facilities, pumping stations, garbage segregation plants, and other mechanical facilities.
• Environmental engineering or environmental systems courses oriented towards a civil engineering approach in which structures and the landscape are constructed to blend with or protect the environment.
• Environmental chemistry , sustainable chemistry or environmental chemical engineering courses oriented towards understanding the effects of chemicals in the environment, including any mining processes, pollutants, and also biochemical processes.
• Environmental technology courses oriented towards producing electronic or electrical graduates capable of developing devices and artifacts able to monitor, measure, model and control environmental impact, including monitoring and managing energy generation from renewable sources.

### Curriculum

The following topics make up a typical curriculum in environmental engineering: [19]

1. Mass and Energy transfer
2. Environmental chemistry
3. Growth models
4. Risk assessment
1. Hazard identification
2. Dose-response Assessment
3. Exposure assessment
4. Risk characterization
5. Comparative risk analysis
5. Water pollution
1. Water resources and pollutants
2. Oxygen demand
3. Pollutant transport
4. Water and waste water treatment
6. Air pollution
1. Industry, transportation, commercial and residential emissions
2. Criteria and toxic air pollutants
3. Pollution modelling (e.g. Atmospheric dispersion modeling)
4. Pollution control
5. Air pollution and meteorology
7. Global change
1. Greenhouse effect and global temperature
2. Carbon, nitrogen, and oxygen cycle
3. IPCC emissions scenarios
4. Oceanic changes (ocean acidification, other effects of global warming on oceans) and changes in the stratosphere (see Physical impacts of climate change)
8. Solid waste management and resource recovery
1. Life cycle assessment
2. Source reduction
3. Collection and transfer operations
4. Recycling
5. Waste-to-energy conversion
6. Landfill

## Mass Balance

Consider a man made chemical that we wish to find the fate of in relation to time, position, some phase of matter, or flow of a liquid. We represent the measured change in concentration as a function of all the rates of change that effect that clump of chemical matter.

${\displaystyle V{dC \over dt}=\sum ({d^{b}m \over dt^{b}})}$

Meaning that for some control volume, the change in concentration versus change in linear independent time is equal to the sum of whatever changes are occurring in (+) and out(-) of that control volume. This is allowed for a few different reasons:

${\displaystyle totalmass=mass_{a}+mass_{b}+mass_{c}...mass_{n}}$

(2) Representation as an ordinary differential equation.

${\displaystyle a_{0}(x)y+a_{1}(x)y'+a_{2}(x)y''+\cdots +a_{n}(x)y^{(n)}+b(x)=0,}$

(3) A solution exists.

Although differential equations can be intimidating, this formula for a change in the concentration for a control volume per time is very versatile even without calculus. Take for instance the common scenario of a tank containing a volume with a contaminant of a certain concentration. Given that there is a first order reaction -kC taking place and that the tank is in steady state the effluent concentration becomes an expression of the initial concentration, the reaction constant k, and the hydraulic retention time (HRT) which is equal to the quotient of the volume of the tank by the flow.

${\displaystyle C=C_{0}/(1+\tau *k)}$

## Applications

### Water supply and treatment

Environmental engineers evaluate the water balance within a watershed and determine the available water supply, the water needed for various needs in that watershed, the seasonal cycles of water movement through the watershed and they develop systems to store, treat, and convey water for various uses.

Water is treated to achieve water quality objectives for the end uses. In the case of a potable water supply, water is treated to minimize the risk of infectious disease transmission, the risk of non-infectious illness, and to create a palatable water flavor. Water distribution systems [20] [21] are designed and built to provide adequate water pressure and flow rates to meet various end-user needs such as domestic use, fire suppression, and irrigation.

### Wastewater treatment

There are numerous wastewater treatment technologies. A wastewater treatment train can consist of a primary clarifier system to remove solid and floating materials, a secondary treatment system consisting of an aeration basin followed by flocculation and sedimentation or an activated sludge system and a secondary clarifier, a tertiary biological nitrogen removal system, and a final disinfection process. The aeration basin/activated sludge system removes organic material by growing bacteria (activated sludge). The secondary clarifier removes the activated sludge from the water. The tertiary system, although not always included due to costs, is becoming more prevalent to remove nitrogen and phosphorus and to disinfect the water before discharge to a surface water stream or ocean outfall. [22]

### Air pollution management

Scientists have developed air pollution dispersion models to evaluate the concentration of a pollutant at a receptor or the impact on overall air quality from vehicle exhausts and industrial flue gas stack emissions. To some extent, this field overlaps the desire to decrease carbon dioxide and other greenhouse gas emissions from combustion processes.

### Environmental impact assessment and mitigation

Environmental engineers apply scientific and engineering principles to evaluate if there are likely to be any adverse impacts to water quality, air quality, habitat quality, flora and fauna, agricultural capacity, traffic, ecology, and noise. If impacts are expected, they then develop mitigation measures to limit or prevent such impacts. An example of a mitigation measure would be the creation of wetlands in a nearby location to mitigate the filling in of wetlands necessary for a road development if it is not possible to reroute the road.

In the United States, the practice of environmental assessment was formally initiated on January 1, 1970, the effective date of the National Environmental Policy Act (NEPA). Since that time, more than 100 developing and developed nations either have planned specific analogous laws or have adopted procedure used elsewhere. NEPA is applicable to all federal agencies in the United States. [23]

## Regulatory agencies

### Environmental Protection Agency

The U.S. Environmental Protection Agency (EPA) is one of the many agencies that work with environmental engineers to solve key issues. An important component of EPA's mission is to protect and improve air, water, and overall environmental quality in order to avoid or mitigate the consequences of harmful effects.

## Related Research Articles

Environmental science is an interdisciplinary academic field that integrates physical, biological and information sciences to the study of the environment, and the solution of environmental problems. Environmental science emerged from the fields of natural history and medicine during the Enlightenment. Today it provides an integrated, quantitative, and interdisciplinary approach to the study of environmental systems.

Sewage sludge is the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is connected to simple on-site sanitation systems, such as septic tanks.

Industrial waste is the waste produced by industrial activity which includes any material that is rendered useless during a manufacturing process such as that of factories, mills, and mining operations. Types of industrial waste include dirt and gravel, masonry and concrete, scrap metal, oil, solvents, chemicals, scrap lumber, even vegetable matter from restaurants. Industrial waste may be solid, semi-solid or liquid in form. It may be hazardous waste or non-hazardous waste. Industrial waste may pollute the nearby soil or adjacent water bodies, and can contaminate groundwater, lakes, streams, rivers or coastal waters. Industrial waste is often mixed into municipal waste, making accurate assessments difficult. An estimate for the US goes as high as 7.6 billion tons of industrial waste produced annually, as of 2017. Most countries have enacted legislation to deal with the problem of industrial waste, but strictness and compliance regimes vary. Enforcement is always an issue.

Water pollution is the contamination of water bodies, usually as a result of human activities, in such a manner that negatively affects its legitimate uses. Water pollution reduces the ability of the body of water to provide the ecosystem services that it would otherwise provide. Water bodies include for example lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants are introduced into these water bodies. For example, releasing inadequately treated wastewater into natural waters can lead to degradation of these aquatic ecosystems. All plants and organisms living in or being exposed to polluted water bodies can be impacted. The effects can damage individual species and impact the natural biological communities they are part of. Water pollution can also lead to water-borne diseases for people using polluted water for drinking, bathing, washing or irrigation.

Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes. The treatment process takes place in a wastewater treatment plant. There are several kinds of wastewater which are treated at the appropriate type of wastewater treatment plant. For domestic wastewater, the treatment plant is called a sewage treatment plant. For industrial wastewater, treatment either takes place in a separate industrial wastewater treatment plant, or in a sewage treatment plant. Further types of wastewater treatment plants include agricultural wastewater treatment plants and leachate treatment plants.

The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibilities of the states in addressing pollution and providing assistance to states to do so, including funding for publicly owned treatment works for the improvement of wastewater treatment; and maintaining the integrity of wetlands.

Biosolids are solid organic matter recovered from a sewage treatment process and used as fertilizer. In the past, it was common for farmers to use animal manure to improve their soil fertility. In the 1920s, the farming community began also to use sewage sludge from local wastewater treatment plants. Scientific research over many years has confirmed that these biosolids contain similar nutrients to those in animal manures. Biosolids that are used as fertilizer in farming are usually treated to help to prevent disease-causing pathogens from spreading to the public.

Industrial wastewater treatment describes the processes used for treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater may be reused or released to a sanitary sewer or to a surface water in the environment. Some industrial facilities generate wastewater that can be treated in sewage treatment plants. Most industrial processes, such as petroleum refineries, chemical and petrochemical plants have their own specialized facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the regulations regarding disposal of wastewaters into sewers or into rivers, lakes or oceans. This applies to industries that generate wastewater with high concentrations of organic matter, toxic pollutants or nutrients such as ammonia. Some industries install a pre-treatment system to remove some pollutants, and then discharge the partially treated wastewater to the municipal sewer system.

Onsite sewage facilities (OSSF), also called septic systems, are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater, in areas not served by public sewage infrastructure.

Milorganite is a brand of biosolids fertilizer produced by treating sewage sludge by the Milwaukee Metropolitan Sewerage District. The term is a portmanteau of the term Milwaukee Organic Nitrogen. The sewer system of the District collects municipal wastewater from the Milwaukee metropolitan area. After settling, wastewater is treated with microbes to break down organic matter at the Jones Island sewage treatment plant in Milwaukee, Wisconsin. The byproduct sewage sludge is produced. This is heat-dried with hot air in the range of 900–1,200 °F (482–649 °C), which heats the sewage sludge to at least 176 °F (80 °C) to kill pathogens. The material is then pelletized and marketed throughout the United States under the name Milorganite. The result is recycling of the nitrogen and phosphorus from the waste-stream as fertilizer. The treated wastewater is discharged to Lake Michigan.

Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that include algorithms to solve the mathematical equations that govern the pollutant dispersion. The dispersion models are used to estimate the downwind ambient concentration of air pollutants or toxins emitted from sources such as industrial plants, vehicular traffic or accidental chemical releases. They can also be used to predict future concentrations under specific scenarios. Therefore, they are the dominant type of model used in air quality policy making. They are most useful for pollutants that are dispersed over large distances and that may react in the atmosphere. For pollutants that have a very high spatio-temporal variability and for epidemiological studies statistical land-use regression models are also used.

Secondary treatment is the removal of biodegradable organic matter from sewage or similar kinds of wastewater. The aim is to achieve a certain degree of effluent quality in a sewage treatment plant suitable for the intended disposal option. This is achieved with physical phase separation to remove settleable solids followed by a biological process to remove dissolved and suspended organic compounds. Secondary treatment is the portion of a sewage treatment sequence removing dissolved and colloidal compounds measured as biochemical oxygen demand (BOD). Secondary treatment is traditionally applied to the liquid portion of sewage after primary treatment has removed settleable solids and floating material. Secondary treatment is usually performed by microorganisms in a managed aerobic habitat or less commonly by an anaerobic process. Bacteria and protozoa consume biodegradable soluble organic contaminants while reproducing to form cells of biological solids. Secondary treatment by biochemical oxidation of dissolved and colloidal organic compounds is widely used in sewage treatment and is applicable to some agricultural and industrial wastewaters.

Best management practices (BMPs) is a term used in the United States and Canada to describe a type of water pollution control. Historically the term has referred to auxiliary pollution controls in the fields of industrial wastewater control and municipal sewage control, while in stormwater management and wetland management, BMPs may refer to a principal control or treatment technique as well.

Sanitary engineering, also known as public health engineering or wastewater engineering, is the application of engineering methods to improve sanitation of human communities, primarily by providing the removal and disposal of human waste, and in addition to the supply of safe potable water. Traditionally a branch of civil engineering and now a subset of environmental engineering, in the mid-19th century, the discipline concentrated on the reduction of disease, then thought to be caused by miasma. This was accomplished mainly by the collection and segregation of sewerage flow in London specifically, and Great Britain generally. These and later regulatory improvements were reported in the United States as early as 1865.

Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater. There is a high number of sewage treatment processes to choose from. These can range from decentralized systems to large centralized systems involving a network of pipes and pump stations which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant.

The CSIR-National Environmental Engineering Research Institute (CSIR-NEERI) is a research institute created and funded by Government of India. It was established in Nagpur in 1958 with focus on water supply, sewage disposal, communicable diseases and to some extent on industrial pollution and occupational diseases found common in post-independent India. NEERI is a pioneer laboratory in the field of environmental science and engineering and part of Council of Scientific and Industrial Research (CSIR). NEERI has five zonal laboratories at Chennai, Delhi, Hyderabad, Kolkata and Mumbai. NEERI falls under the Ministry of Science and Technology (India) of the central government. The NEERI is an important partner organisation in India's POPs national implementation plan (NIP).

Sewage is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality. Sub-types of sewage are greywater and blackwater. Sewage also contains soaps and detergents. Food waste may be present from dishwashing, and food quantities may be increased where garbage disposal units are used. In regions where toilet paper is used rather than bidets, that paper may be added to sewage rather than placed with municipal solid waste. Sewage may contain micro-pollutants and pollutants from industrial wastewater.

The term Environmental persistent pharmaceutical pollutants (EPPP) was first suggested in the nomination in 2010 of pharmaceuticals and environment as an emerging issue in a Strategic Approach to International Chemicals Management (SAICM) by the International Society of Doctors for the Environment (ISDE). The occurring problems from EPPPs are in parallel explained under environmental impact of pharmaceuticals and personal care products (PPCP). The European Union summarizes pharmaceutical residues with the potential of contamination of water and soil together with other micropollutants under “priority substances”.

Groundwater pollution occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted constituent, contaminant, or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution. Pollution can occur from on-site sanitation systems, landfills, effluent from wastewater treatment plants, leaking sewers, petrol filling stations or from over application of fertilizers in agriculture. Pollution can also occur from naturally occurring contaminants, such as arsenic or fluoride. Using polluted groundwater causes hazards to public health through poisoning or the spread of disease.

## References

1. "Careers in Environmental Engineering and Environmental Science". American Academy of Environmental Engineers & Scientists. Retrieved 2019-03-23.
2. "Architecture and Engineering Occupations". Occupational Outlook Handbook. Bureau of Labor Statistics. 20 February 2019. Retrieved 23 March 2019.
3. "10 Advancements in Environmental Engineering". HowStuffWorks. 2014-05-18. Retrieved 2019-03-23.
4. Beychok, Milton R. (1967). Aqueous Wastes from Petroleum and Petrochemical Plants (1st ed.). John Wiley & Sons. LCCN   67019834.
5. Tchobanoglous, G.; Burton, F.L. & Stensel, H.D. (2003). Wastewater Engineering (Treatment Disposal Reuse) / Metcalf & Eddy, Inc (4th ed.). McGraw-Hill Book Company. ISBN   978-0-07-041878-3.
6. Turner, D.B. (1994). (2nd ed.). CRC Press. ISBN   978-1-56670-023-8.
7. Beychok, M.R. (2005). Fundamentals Of Stack Gas Dispersion (4th ed.). author-published. ISBN   978-0-9644588-0-2.
8. (9th ed.). Macmillan Reference. 2007.
9. "Become Board Certified in Environmental Engineering". American Academy of Environmental Engineers & Scienteists. Retrieved 2019-03-23.
10. "NCEES PE Environmental exam information". NCEES. Retrieved 2019-03-23.
11. "Professional Engineering Institutions". Engineering Council. Retrieved 2019-03-23.
12. "environ | Search Online Etymology Dictionary". www.etymonline.com. Retrieved 2020-12-14.
13. Mason, Matthew. "Environmental Engineering: Why It's Vital for Our Future". Environmental Science. Retrieved 2019-03-23.
14. Jansen, M. (October 1989). "Water Supply and Sewage Disposal at Mohenjo-Daro". World Archaeology. 21 (2): 177–192. doi:10.1080/00438243.1989.9980100. JSTOR   124907. PMID   16470995.
15. Angelakis, Andreas N.; Rose, Joan B. (2014). "Chapter 2: "Sanitation and wastewater technologies in Harappa/Indus valley civilization (ca. 2600-1900 BC)". Evolution of Sanitation and Wastewater Technologies through the Centuries. IWA Publishing. pp. 25–40. ISBN   9781780404851.
16. "Funding - Environmental Engineering". US National Science Foundation. Retrieved 2013-07-01.
17. "Waterborne Infections". Encyclopedia.com. Retrieved 2019-03-23.
18. Radniecki, Tyler. "What is Environmental Engineering?". College of Engineering. Oregon State University. Retrieved 2019-03-23.
19. Masters, Gilbert (2008). Introduction to environmental engineering and science. Upper Saddle River, N.J: Prentice Hall. ISBN   978-0-13-148193-0.
20. Drinking water distribution systems : assessing and reducing risks. National Academies Press. 2006. ISBN   978-0-309-10306-0 . Retrieved 6 October 2019.
21. "Water Distribution Networks CE370" (PDF). King Fahd University of Petroleum and Minerals. Retrieved 6 October 2019.
22. Sims, J. (2003). Activated sludge, Environmental Encyclopedia. Detroit.
23. (3rd ed.). McGraw-Hill, Inc. 1993.
• Davis, M. L. and D. A. Cornwell, (2006) Introduction to environmental engineering (4th ed.) McGraw-Hill ISBN   978-0072424119
• National Academies of Sciences, Engineering, and Medicine (2019). Environmental Engineering for the 21st Century: Addressing Grand Challenges (Report). Washington, DC: The National Academies Press. doi:10.17226/25121.CS1 maint: multiple names: authors list (link)